Method and system for controlling the operation of devices in a hydrocarbon production system

ABSTRACT

A system for controlling the operation of devices ( 61, 62, 63 ) of a hydrocarbon production system has two reprogrammable central controllers ( 100 ) contained-in a retrievable module ( 49   a ) of a seabed facility ( 20 ′) associated with a hydrocarbon field ( 170 ). Local controllers are configured to control the operation of specific devices, such as actuators ( 61 ), sensors ( 62 ) and valves ( 63 ) within the module ( 49   a ) and within tree wellheads ( 30 ′) of the field ( 170 ) and are locally connected to these devices ( 61, 62, 63 ). A single common data bus ( 130 ) links the central controllers ( 100 ),and the local controllers and enables data to be transmitted between the central controllers ( 100 ) and the local controllers in response to the central controllers ( 100 ) receiving signals. Each local controller has a microprocessor for processing the data transmitted to it, and the processed data is transmitted between the local controller and its associated devices ( 61, 62, 63 ) in accordance with the processed data so as to locally control the operation of those device.

The present invention relates to a method and system for controlling theoperation of devices in a hydrocarbon production system, and moreparticularly, to a system for controlling devices in a subsea system.

When developing hydrocarbon production systems, system components anddevices, such as pumps, temperature sensors and the like are initiallyselected and a control system is subsequently designed specifically tocontrol the operation of the selected devices. If an additional deviceis later required, the control system has to be replaced or upgradedunless the control system has remaining, finite, capacity. Consequently,during the initial system design stage, a best estimate of futureequipment requirements has to be made. As production characteristicsvary enormously throughout field life, it is impossible to know exactlywhen or if new equipment will be required, in fact, by the timeadditional equipment is required, the desired specification of theadditional equipment may be completely different to that identifiedduring initial design. It is therefore desirable to design a system thatcan cater for incremental field development without the need to shutdown the system due to hardware changes.

FIG. 1. of the accompanying drawings, shows an existing control systemfor controlling a single field of a subsea hydrocarbon production system10. A host facility 11, which may be, for example, onshore or on a fixedor floating rig, has a master control station and a power supply (notshown) which are connected to a remote seabed facility 20 and wellheadtrees 30 on the seabed 80, via a remote subsea distribution module (SDM)40 by power and signal cables 12. Fluid pipelines (not shown) areconnected from the host facility to the seabed facility 20 and thewellhead trees 30 so as to allow fluid to be passed around the systemunder control of the control system.

The seabed facility 20 comprises a retrievable module 49 connected to abase structure, in this case a manifold 21, on the seabed 80 by cableconnectors 22 and a multi-ported fluid connector (not shown). In theexample shown in FIG. 1, the module 49 contains a subsea control module(SCM) and of the general type forming part of a modular system forsubsea use designed by Alpha Thames Limited of Essex, United Kingdom,and referred to as AlphaPRIME.

The SCM 50 contains a subsea electronic module (SEM) 51 which containshardware and software and which is designed exclusively to control theoperation of specific devices 60 which are contained in the SCM 50 orwhich are to be added based on possible future requirements of thesystem as determined when the SEM 51 is first installed in the module49. The devices 60 may include electrically actuated valves manufacturedunder the names PROACT and REACT by Alpha Thames Limited and separators.Messages are passed back and forth to the host facility by the SEM ofthe SCM.

Further SCMs 70 and SEMs 71 which comprise simple electronic circuitsare also contained within the wellhead trees 30 themselves and receivethe electrical signals from the SEM 51 of the SCM 50 to operate otherdevices, such as valves and sensors (not shown), contained in thewellhead trees. The wellhead trees 30 connect onto the SDM 40 to providetheir communications. All communication to and from the trees 30 has topass via the host facility 11.

The number of devices which can be controlled is limited by the capacityof the SEM. The SCM is a thin walled oil filled, pressure balancedhydraulic device. Conventionally, the SCM receives high pressurehydraulic fluid from the host to power the hydraulically operated valveson the tree/manifold. The SEM is a gas filled thick walled pressure,vessel normally comprising a cylinder of approximately 100 mm diametercontaining electron capacity in the form of microchips, printed circuitboards etc. The electronics in. the STEM receive control signals fromthe host and convert these into simple electrical signals that operatesimple shuttle valves, etc contained in the SCM to control the highpressure hydraulic fluid to open and close production valves on thewellhead trees. The design engineer has to predict the expansion ofcontrolled equipment likely over the field life on the manifold andwellhead trees However, every additional connection to the SCM 50,70 andSEM 51,71 contained therein are additional failure points, and sopossible future expansion is weighed against system reliability.

There are also limitations on the size of the field. Subsea distributionmodules (SDM) can be chained together to connect more SCMs 50,70 andSEMs 51,71 together but with each additional unit there is an additionalloss, so there is a finite size to the field.

The SEMs 51,71 of the SCMs 50,70 have physical limits on the number ofconnections that can be made to devices. Cables have to exit the casingof the SEM, via penetrators. As the SEM is at atmospheric pressure andthe outside pressure could be 300 times that, the cross section of thepenetrator must be as small as possible. As the cross sectional areaincreases the effect of the outside pressure will be to push thepenetrator or cables through the wall of the SEM and into the SEM andcompromise the seal. As more and more cables are required to connect tooutside devices the cost to seal the SEM 51,71 of theSCM 50,70increases. Shown on FIG. 1 are lines between the SEM of the SCM and thedevices 60. Each line comprises a bundle of cables 53 to control thedevice. Each bundle requires an SEM penetrator, on a basic system therecould be 15 or more penetrators, which significantly increases thecomplexity and cost of the system.

As technology is progressing at a significant pace, current fielddevelopment control systems limit the ability to add new functionality.or new technology.

In order to embrace new technology, particularly for subsea fielddevelopments, it is important to have readily maintainable andupgraedeable modular systems that can allow for future expansion asequipment improves over time. It is also important to ensure that thecontrol and powering of these systems also takes a modular form and cankeep pace with system changes without the need to change the hardwareduring field life.

There is a need to provide a method and system for controlling devicesof a hydrocarbon production system which enables the production systemto be upgraded or modified over time without recourse to changes ininstrument and control hardware.

According to one aspect, the present invention consists in a method forcontrolling the operation of devices of a hydrocarbon production system,comprising the steps of:

(a) connecting at least one central controller to at least one localcontroller, the central controller(s) being reprogrammable and the localcontroller(s) being configured to locally control the operation of atleast one respective device,

(b) transmitting data between the central controller(s) and the localcontroller(s) in response to said central controller(s) receivingsignals

(c) processing said transmitted data at the local controller(s), and

(d) transmitting data between the local controller(s) and its associateddevice(s) according to the processed data so as to locally control theoperation of the devices(s).

By using a local controller to locally control specific devices andreprogrammable central controllers to control, the local controllerscontrol of existing devices can be modified or new devices and theirlocal controllers can be subsequently added to any part of the systemwithout requiring hardware changes to the central controllers.

Preferably, the method step (b) includes transmitting data between thecentral controller(s) and the local controller(s) in response to saidcentral controller(s) receiving signals from n any other centralcontroller, or alternatively or additionally from the localcontroller(s). The method according to this latter mentioned featureallows the central controller(s) to operate independently of a hostfacility.

Additionally, the method may include the steps of:

(e) connecting a remote master controller to the central controller(s),

(f) transmitting data between the master controller(s) and the centralcontroller(s) so as to remotely monitor the central controller(s).

Alternatively or additionally, the method may include the steps of

(g) transmitting data between the remote master controller(s) and thecentral controller(s) so as to reprogram the central controller(s) toenable newly added devices and their local controllers to be used in theaforementioned method or to enable the central controller(s) to controlexisting local controllers in a different manner.

Preferably, the method includes a step of feeding back data signals fromthe device(s) to the local controller(s), for example, in response tothe device(s) receiving data or activating.

Also preferably, the method includes the step of feeding back datasignals from the local controller(s) to the central controller(s), forexample, in response to the local controller(s) receiving feedback datasignals from its associated device(s) or from the central controller(s).

Additionally, the method step (d) may include controlling the device(s)by activating or powering a sensor or valve, actuating a compressor,pump or actuator.

In a preferred embodiment, at least two central controllers arecontained in one or more subsea control modules of retrievable modulesof one or more field developments. The central local controllers aremicroprocessors or central processing units. Local controllers areconnected to their associated devices such as, motors, temperaturesensors, pressure sensors, or magnet valves, which are contained in theor each control module itself, in wellhead trees and any other type ofsubsea apparatus suitable for use with a subsea hydrocarbon productionsystem. The method of the invention enables the devices and their localcontrollers to be connected to the or each central controller via acommon data bus so that the number and size of penetrators used in thesystem can be kept to a minimum.

Additionally, in the preferred embodiment the method may include thestep of connecting the central controller of one subsea control moduleto one or more central controllers contained in one or more other subseacontrol modules in the same or another field development, transmittingdata between any of the central controllers and any of the localcontrollers contained in one of said subsea modules or a tree of thesame or another field development. For example, the method may includethe step of transmitting data from a sensor to its local controller inresponse to the sensor detecting an excess of fluid in a first field,transmitting data from the local controller back to a first centralcontroller of a subsea control module of the first field, transmittingdata between the first central controller and one or more other centralcontrollers contained in any subsea control modules in the same andother fields to determine a second field which has a shortage orsuitable outlet, and transmitting data between the first centralcontroller and other local controllers in the same and other fields soas to control a device in the second field to allow excess fluid to betransferred from the first field to the second field.

According to another aspect, the present invention consists in a systemfor controlling the operation of devices of a hydrocarbon productionsystem, comprising:

(a) connecting, means for connecting at least one central controller toat least one local controller, the central controller(s) beingreprogrammable and the local controller(s) being configured to locallycontrol the operation of at least one respective device,

transmitting means for transmitting data between, the centralcontroller(s) and the local controller(s) in response to said centralcontroller(s) receiving signals,

(c) processing means for processing said transmitted data at the localcontroller(s), and

(d) transmitting means for transmitting data between the localcontroller(s) and its associated device(s) according to the processeddata so as to locally control the operation of the device(s).

Preferably, the system includes control means for remotely controllingthe central controller(s) and transmitting means for transmitting databetween the master control means and the central controllers so as toremotely monitor the central controller(s).

Alternatively or additionally, a system may include transmitting meansfor transmitting data between the master controlling means and thecentral controller(s) so as to reprogram the central controller(s) toenable new devices and their local controllers to be controlled by thecentral controller(s) or to enable the central controller(s) to controlthe existing local controller(s) and in a different manner.

Preferably, the system includes means for feeding back data signals fromthe device(s) to the local controller(s) and from the localcontroller(s) to the central controller(s).

According to yet another aspect, the present invention comprises acomputer program product comprising program code means stored in acomputer readable medium for performing a method according to any one ofthe method steps of any one of the aforementioned methods when thatproduct is run on a computer.

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a subsea hydrocarbon production systemaccording to the prior art;

FIG. 2 is a schematic diagram of a system according to a preferredembodiment of the present invention;

FIG. 3 is a block diagram showing the logical layout of the system shownin FIG. 2;

FIG. 4 is a block diagram showing the logical layout and interaction ofthe first layers of the software which is run on the system of FIG. 2;

FIG. 5 is a schematic diagram of the system of FIG. 2 but with one ofthe system modules reconfigured to include several additional localcontrollers and devices; and

FIG. 6 is a schematic diagram showing adjacent fields connected to eachother by pipelines, power lines and communication lines.

Referring to FIG. 2 of the accompanying drawings, the system forcontrolling the operation of a hydrocarbon system has two centralcontrollers 100 contained in a first subsea control module 50 a of aretrievable module 49 a which is connected to a manifold 21′ of a seabedfacility 20′. A command/signal bus 120 links a master control station101 contained in a host facility 11′ to each of the central controllers100 of the first retrievable module 49 a via a manifold 21′. The hostfacility 11′ is, for example, onshore or on a fixed or floating rig andthe master control station 101 comprises a processing means which, inthis embodiment, is a central processing unit. The command/signal bus120 also links the central controllers 100 of the first retrievablemodule 49 a and the master control station 101 to any other mastercontrol station (not shown) and any other central controller existing inthe same170 or a different field.

Local controllers are locally connected to one or more specific devices,such as actuators 61, sensors 62, valves 63 and pumps (not shown)contained within the first retrievable module 49 a and within each treewellhead 30′. The local controllers and the central controllers 100 arelinked to a common data bus 130 so that data may be transmitted betweenthe central controllers 100 and the local controllers and between thecentral controllers 100 themselves. Furthermore, the one or morespecific devices can only communicate via the single common data bus 130to local central controllers 100 within that field 170 andcommunications between the field 170 and any other field (not shown) isvia the command/signal bus 120.

Each local controller comprises a processing means, such as amicroprocessor, which is appropriately programmed to permit it locallyto control and run its associated device or devices 61-63 in response tosimple commands which are sent to it from one of the central controllers100;

Thus, instead of all the processing power of the control system being ina central place, the devices 61-63 of the system are controlled locallyby local controllers which have their own processing power. Each localcontroller has enough processing power and programming to control thedevice or devices 61-63 which are locally connected to it. All commandsissued to each device 61-63 can be as simple as move here, do this etc.Each device 61-63 can be queried for its current status, during or aftera procedure. Feedback when a device has finished a command can also befed back to the central controllers 100 via the local controllers. Aswill be explained more fully below, this, means that any processingwhich is specific to a device 61-63 can be performed within its localcontroller. The central controllers 100 therefore only require newsoftware and not new hardware to control a new device.

As shown in FIG. 2, a second retrievable subsea module 49 b which isidentical to the first module 49 a is connected to the manifold 21′ at aposition adjacent to the position at which the first module 49 a isconnected so that if the first module 49 a becomes inoperable, forexample through failure or as a consequence of it being retrieved forservicing, a second module 49 b can be used to perform all the functionsof the first module without interrupting operation of the productionsystem. To this end, the central controllers 100 of the second module 49b are connected to the common command/signals bus 120 so that the mastercontrol station(s) 101 may transmit the command/signals to not only thecentral controllers 100 of the first module but also the centralcontrollers 100 in the second module 49 b. Likewise, the localcontrollers and central controllers 100 contained in the second module49 b are connected to he common data bus 130 so that data can betransmitted between the central controllers 100 of the second module 49b and between any other central controller 100 and between the localcontrollers contained in the second module 49 b and any other centralcontroller.

FIG. 3 shows the logical layout of the system of the field 170 shown inFIG. 2 and part of an additional field 180. The layout is split intofour layers. At the bottom is the Device Layer 201. This layer containsall the sensors 61-63, motors etc for each device, i.e. the componentsof each device. The next layer up is the Device Control Layer 202. Thisis the layer that contains the local controller for each device 61-63.Each local controller is programmed to deal with the functionality ofthe device 61-63. These two layers 201,202 may be combined to provide socalled “Smart Devices”. The next layer up is the system control layer203. This contains the central controller 100 that binds the SmartDevices together and makes them perform their tasks according to thesystem programming.

Redundancy is provided by a voting system between central controllers100 contained within the subsea system. The voting system is based onthe central controllers 100 in different subsea control modules of thesame field 170 communicating with each other to provide a mechanismwhereby a controller 100 that is found to beat fault is ignored.

The top layer shown in FIG. 3 is the Master Control Layer 204.Monitoring is performed here and system configuration changes aredeployed from here. In this embodiment, many master controllers 101 aremonitoring the subsea systems, or selectively monitoring their specificfield development. Throughout this network, communication is onlypossible between device/controllers at the same level or on immediatelyadjacent levels.

FIG. 4 shows the logical layout and interaction of the various, layersof the software portion of the invention. The “Connectivity layer” 300standardises the interface to the network. This functions as anabstraction layer so that many different types of networking can beused. The “Core Layer” 301 sits on top of the “Connectivity Layer”. Thislayer 301 provides many functions. Firstly it unifies the networkconnections together. Secondly it provides another abstraction layer, atthis layer 301 local controller discovery and communication etc isprovided. Anything common to all local controllers is provided here. Thefinal layer that makes up the “Kernel” portion of the system is the“Device Driver Layer” 302. At this layer 302, many local controllerdrivers are provided, These provide the specific control, and feedback,to the local controller the driver is written for New devices and theirlocal controllers can be added by just adding a new driver to thecentral controllers.

The next layer 303, which exists in user portion of the system, is theapplication that runs the local controllers and communicates with theother control systems, subsea units and hosts.

The use of “Kernel” and “User” programming techniques allows this to beimplemented using current embedded computing technology.

Software programmes allow the local controller drivers to be readilyupdated without the need to change control hardware. These also allowthe is central controllers to operate all the local controllers andallow for new devices and their local controllers to be added in thesystem. Furthermore the programs allow the central controllers 100 tooperate independently of host equipment.

The central controllers 100 can also communicate with each other, via acommon data bus 130, in a voting system to agree on commands to devicesand ensure that commands from a controller that is issuing commands inerror is ignored.

Central controllers 100 can communicate with central controllers 100 ofother subsea units via the command/signal bus 120 to enable the controlof a nodal subsea hydrocarbon productionl system to be effected. Such asystem may include a network of subsea units connected to one or morehost or fluid receiving facilities by a network of pipelines and controllines connected to permit fluids to be selectively routed through thenetwork in a manner dependent on subsea unit requirements and otherrequirements. The topside host is only for monitoring, systemconfiguration and issuing commands. Software architecture is alsomodular and standardised to allow for easy addition of new devices.

FIG. 6 of a nodal subsea hydrocarbon productions system shows howadjacent fields can be connected to each other by a number of pipelines,power lines and communication lines to make the best use of existinginfrastructure and to avoid the need for long and costly lines back tospecific (possibly distant) host facilities. By enabling communicationand control between the local controllers and central controllers on thefields 170,180, paths can be setup within a mesh or network of pipelines400 (shown with solid lines) to permit excess fluid to be transferredfrom one field 170 to another 180 which has a shortage or suitableoutlet, e.g. excessive water produced at one field can be transferred toa field which is injecting water for reservoir pressure maintenance orfor disposal. Similarly, this mesh of lines may permit alternate routesto be provided for fluid, power or communications should a problem occurwith the, existing route communication lines are shown with dottedlines.

Methods for controlling the operation. of devices of a hydrocarbonproduction system according to preferred embodiments will now bedescribed with reference to the Figures of the accompanying drawings.

Referring to FIG. 2, initially, a central controller 100 of the firstsubsea module 49 a is connected to a local controller of a valve 63contained in a tree 30′ when the module 49 a is appropriately dockedwith the manifold 21′. The central controller 100 receives signals fedback on the common data bus 130 from a sensor 62 contained in the firstsubsea module 49 a via the sensor's local control module. Data is thentransmitted between the central controller 100 and the local controllerof the valve 63. The local controller of the valve then processes thetransmitted data and data is then transmitted between it and the valve63 so as to locally control the operation of the valve 63.

When remote monitoring of the system is required, the remote mastercontrol station 101 is connected to the central controller 100 ofinterest and data is transmitted between the master control station 101and the central controller of interest on the command/signal data bus120 so as to remotely monitor the central controller and any othercontrollers or devices connected to it.

In order to reprogram a central controller 100, a remote master controlstation 101 is connected to the central controller of interest and datais transmitted between the master control station and the centralcontroller on the command/signal bus 120 so as to reprogram the centralcontroller for the aforementioned purposes.

In order to upgrade the field without significant disruption toproduction, the subsea module 49 b shown in FIG. 2 is retrieved andreconfigured to include several additional devices 64 and their localcontrollers. The local controllers are added to the data bus within themodule 49 c and the relevant drivers and updated control program areinstalled. The reconfigured module 49 c is then installed on the fieldand commissioned. FIG. 5 shows the reconfigured subsea module 49 c. Oncefully operational, the control program is updated in thenon-reconfigured module 48 a so that normal operation including voting,and redundancy, etc is restored. In due course, the other module 48 acan be reconfigured in a similar manner.

Referring to FIGS. 2 and 6, a central controller 100 of one subseacontrol module 48 a is connected to central controllers 100 containedother subsea control modules in the same and other field developments170,180. Data is fed back on the data bus 130 from a sensor 62 via itslocal controller to a first central controller 100 contained in thesubsea control module 48 a in response to the sensor 62 detecting anexcess of fluid in the field 170. The first central controller or mastercontrol station 101 of the first field 170 communicates with the othercentral controllers of all the fields to determine a second field whichhas a shortage of fluid or a suitable outlet. Data is then transmittedbetween the first central controller and other central controllers 100contained in subsea control modules in other fields. Data is thentransmitted between the second central controller of the first field 170and local controllers in the first and other fields so as to controlvalves 63 in the first and other fields to allow excess fluid to betransferred from the first field to the second field.

The system for controlling the operation of a hydrocarbon system mayenable routing of fluids to be changed, and this needs to be confirmedvia the master control station 101 in a host facility 11′.

1. A method for controlling the operation of devices (61,62,63) of ahydrocarbon production system, comprising the steps of: (a) connectingat least one central controller (100) to at least one local controller,the central controller(s) (100) being reprogrammable and the localcontroller(s) being configured to locally control the operation of atleast one respective device (61,62,63), (b) transmitting data betweenthe central controller(s) (100) and the local controller(s) in responseto said central controller(s) (100) receiving signals, (c) processingsaid transmitted data at the local controller(s), and (d) transmittingdata between the local controller(s) and its associated device(s)(61,62,63) according to the processed data so as to locally control theoperation of the device(s) (61,62,63).
 2. The method as claimed in claim1, wherein method step (b) includes transmitting data between thecentral controller(s) (100) and the local controller(s) in response tosaid central controller(s) (100) receiving signals from any othercentral controller, and/or from the local controller(s).
 3. The methodas claimed in claim 1 or 2, including the step of connecting at leastone remote master controller (101) to the central controller(s) (100).4. The method as claimed in claim 3, including the step of transmittingdata between the master controller(s) (101) and the centralcontroller(s) (100) so as to remotely monitor the central controller(s).5. The method as claimed in claim 3 or 4, including the steps of addingat least one device (64) and its associated local controller(s) to thehydrocarbon production system, transmitting data between the remotemaster controller(s) (101) and the central controller(s) (100), andreprogramming the central controller(s) (100) to enable said newly addeddevice(s) (64) and its local controller(s) to be used in the method. 6.The method as claimed in claim 3, 4 or 5, including. the steps oftransmitting data between the remote master controller(s) (101) and thecentral controller(s) (100), and reprogramming the central controller(s)(100) to enable the central controller(s) (100) to control existinglocal controllers in a different manner.
 7. The method as claimed in anypreceding claim, including the step of feeding back data signals fromthe device(s) (61,62,63) to the local controller(s).
 8. The method asclaimed in any preceding claim, including the step of is feeding backdata signals from the local controller(s) to the central controller(s)(100).
 9. The method as claimed in any preceding claim, wherein methodstep (d) includes controlling the device(s) (61,62 63) by at leastactivating or powering a sensor (62) and/or valve (63), and/or actuatinga compressor, pump and/or actuator (61).
 10. The method as claimed inany preceding claim, including the step of connecting the centralcontroller (100) of one subsea control module (50 a). to one or morecentral controllers (100) contained in one or more other subsea controlmodules (50 b) in the same or another field development (170,180), andwherein method step (b) comprises transmitting data between any of thecentral controllers (100) and any of the local controllers contained ina retrievable module (48 a,49 b) or a tree (30′) of the same or anotherfield development (170,180).
 11. A system for controlling the operationof devices (61,62,63) of a hydrocarbon production system, comprising:(a) connecting means (130) for connecting at least one centralcontroller (100) to at least one local controller, the centralcontroller(s) being reprogrammable and the local controller(s) beingconfigured to locally control the operation of at least one respectivedevice (61,62,63), (b) transmitting means (130) for transmitting databetween the central controller(s) (100) and the local controller(s) inresponse to said central controller(s) (100) receiving signals, (c)processing means for processing said transmitted data at the localcontroller(s), and (d) transmitting means for transmitting data betweenthe local controller(s) and its associated device(s) (61,62,63)according to the processed data so as to locally control the operationof the device(s).
 12. The system as claimed in claim 11, includingcontrol means (101) for remotely controlling the central controller(s)(100) and transmitting means (120) for transmitting data between themaster control means (101) and the central controller(s) (100).
 13. Thesystem as claimed in claim 11 or 12, including means (130) for feedingback data signals from the device(s) (61,62,63) to the localcontroller(s) and from the local controller(s) to the centralcontroller(s) (100).
 14. A computer program product comprising programcode means stored in a computer readable medium for performing a methodaccording to any one of the method steps as claimed in any one of claims1 to 10 when that product is run on a computer.